1. Field of the Invention
The present invention relates to circuits for detecting shifts in the DC component of an AC signal, an in particular, to circuits for detecting shifts in the baseline of a digital data signal having multiple discrete signal levels.
2. Description of the Related Art
Recovering data which has been transmitted over a long length of cable and through transformers at high data rates requires that such data be equalized in order to compensate for the signal degradation caused by the cable and transformer. Such signal equalization includes frequency compensation and/or DC, or baseline, restoration.
The dc restoration function is necessary to ensure that the equalized incoming signal is properly centered within the dynamic range of the data recovery system so as to allow for accurate signal slicing. The slicing function is performed to ensure that the incoming signal has been properly equalized and is also used to extract the data from the equalized signal.